mirror of
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Ken Colton
a0e33fd384
I noticed that the very next page (which is no longer OSX specific) makes the assumption that `python` will invoke the Python 3 interpreter, while the last mention of versions on this page leaves `python` referencing the OSX System Python interpreter. I honestly do not know if this is the "correct" way to configure this default. It looks like brew is cautious about symlinking over the native Python 2.7.10 (High Sierra) and they might have good reason. All of my projects are Python 3 now, so i'm ready to "make it ~facebook~ PATH official with Python 3" Regardless of how it's done - or if it's a bad idea - it's worth mentioning IMO because there is a discontinuity of where this page leaves `python` and where the next page assumes `python` to be.
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:orphan: This article should not be added to a toctree for now
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.. _install3-osx:
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Installing Python 3 on Mac OS X
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===============================
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.. image:: https://farm5.staticflickr.com/4276/34435689480_2e6f358510_k_d.jpg
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The latest version of Mac OS X, High Sierra, **comes with Python 2.7 out of the box**.
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You do not need to install or configure anything else to use Python 2. These
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instructions document the installation of Python 3.
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The version of Python that ships with OS X is great for learning, but it's not
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good for development. The version shipped with OS X may be out of date from the
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`official current Python release <https://www.python.org/downloads/mac-osx/>`_,
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which is considered the stable production version.
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Doing it Right
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--------------
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Let's install a real version of Python.
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Before installing Python, you'll need to install GCC. GCC can be obtained
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by downloading `XCode <http://developer.apple.com/xcode/>`_, the smaller
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`Command Line Tools <https://developer.apple.com/downloads/>`_ (must have an
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Apple account) or the even smaller `OSX-GCC-Installer <https://github.com/kennethreitz/osx-gcc-installer#readme>`_
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package.
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.. note::
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If you already have XCode installed, do not install OSX-GCC-Installer.
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In combination, the software can cause issues that are difficult to
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diagnose.
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.. note::
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If you perform a fresh install of XCode, you will also need to add the
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commandline tools by running ``xcode-select --install`` on the terminal.
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While OS X comes with a large number of UNIX utilities, those familiar with
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Linux systems will notice one key component missing: a package manager.
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`Homebrew <http://brew.sh>`_ fills this void.
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To `install Homebrew <http://brew.sh/#install>`_, open :file:`Terminal` or
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your favorite OSX terminal emulator and run
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.. code-block:: console
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$ ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
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The script will explain what changes it will make and prompt you before the
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installation begins.
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Once you've installed Homebrew, insert the Homebrew directory at the top
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of your :envvar:`PATH` environment variable. You can do this by adding the following
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line at the bottom of your :file:`~/.profile` file
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.. code-block:: console
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export PATH=/usr/local/bin:/usr/local/sbin:$PATH
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Now, we can install Python 3:
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.. code-block:: console
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$ brew install python3
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This will take a minute or two.
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Pip
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---
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Homebrew installs ``pip3`` for you.
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``pip3`` is the alias to ``pip`` pointing to the Homebrew'd Python 3.
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Working with Python 3
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---------------------
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At this point, you have the system Python 2.7 available, potentially the
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:ref:`Homebrew version of Python 2 <install-osx>` installed, and the Homebrew
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version of Python 3 as well.
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.. code-block:: console
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$ python
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will launch the system Python interpreter.
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.. code-block:: console
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$ python2
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will launch the homebrew-installed Python 2 interpreter (if any).
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.. code-block:: console
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$ python3
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will launch the homebrew-installed Python 3 interpreter.
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If the Homebrew version of Python 2 is installed then ``pip2`` will point to Python 2.
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If the Homebrew version of Python 3 is installed then ``pip3`` will point to Python 3.
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The rest of the guide will assume that ``python`` references Python 3. You can simply choose to always invoke ``python3`` instead, and much is backwards compatible. However, performing the following steps will set Python 3 as the default interpreter for ``python`` in a shell.
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.. code-block:: console
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# Do I have a Python 2 problem?
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$ python --version
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Python 2.7.10 # Referencing OSX system install
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$ which python
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/usr/bin/python # Yup, homebrew's would be in /usr/local/bin
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# Symlink /usr/local/bin/python to python3
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$ ln -s /usr/local/bin/python3 /usr/local/bin/python
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$ python --version
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Python 3.6.4 # Success!
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# If you still see 2.7 ensure in PATH /usr/local/bin/ takes pecedence over /usr/bin/
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Pipenv & Virtual Environments
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-----------------------------
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The next step is to install Pipenv, so you can install dependencies and manage virtual environments.
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A Virtual Environment is a tool to keep the dependencies required by different projects
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in separate places, by creating virtual Python environments for them. It solves the
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"Project X depends on version 1.x but, Project Y needs 4.x" dilemma, and keeps
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your global site-packages directory clean and manageable.
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For example, you can work on a project which requires Django 1.10 while also
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maintaining a project which requires Django 1.8.
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So, onward! To the :ref:`Pipenv & Virtual Environments <virtualenvironments-ref>` docs!
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--------------------------------
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This page is a remixed version of `another guide <http://www.stuartellis.eu/articles/python-development-windows/>`_,
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which is available under the same license.
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